1. Field
The presently disclosed subject matter relates to a projector-type headlight and a configuration structure of a resin projector lens thereof, and especially to a projector-type headlight comprising a projector lens which is a resin molding, and a configuration structure of the resin projector lens.
2. Description of the Related Art
Conventionally, in a projector-type headlight, a light source is provided at a first focal point of an ellipsoidal reflection surface of a reflector or in the vicinity of the first focal point, a shade is provided at a second focal point of the ellipsoidal reflection surface or in the vicinity thereof, and a projector lens is provided on a front side of the second focal point (for example, refer to Japanese Patent Application Laid-Open Publication No. 2008-103192). In such a projector-type headlight, a light emitted from the light source is reflected by the ellipsoidal reflection surface, the reflected light is focused at the second focal point, a part of the reflected light is blocked by the shade, and the reflected light which is not blocked by the shade is projected forward by the projector lens. Since the part of the reflected light is blocked by the shade, a light distribution pattern when two vehicles pass each other, that is, a low beam, is formed.
As a light source of the projector-type headlight, a semi-conductor light emitting device (for example, a light emitting diode), an electric discharge lamp (for example, a high intensity discharge (HID) lamp, a high pressure metal vapor discharge lamp, or the like), a halogen lamp, an incandescent lamp, or the like has been used. Because a wavelength spectrum of the electric discharge lamp, the halogen lamp, and the incandescent lamp contains a large amount of infrared elements, heat is absorbed by the projector lens and the projector lens comes to have a very high temperature. On the other hand, because light emitted from a semi-conductor light emitting device such as a light emitting diode does not contain infrared rays, the projector lens would not be heated to a high temperature.
Therefore, in a case where the electric discharge lamp or the like is used as the light source, the projector lens is molten if a resin molding is used as the projector lens, and due to this reason, a resin molding cannot be used for the projector lens. Meanwhile, in a case where a semi-conductor light emitting device is used as a light source, because of a reason that the light does not contain infrared rays, and the like, the projector lens would not molten even if the resin molding is used as the projector lens, and thus, one can use the resin molding for the projector lens.
Meanwhile, even in a case where the semi-conductor light emitting device is used as the light source, there is a possibility that the projector lens may be deformed due to the heat generated by the element itself or the like, even if the projector lens is not molten. If the projector lens is deformed, optical characteristics of the projector lens are changed and light distribution pattern may be negatively influenced.